Bat Dog 'Rookie' Delays Minor League Game Rushing Onto Field, Adorable Video

A minor league baseball game had a four-legged interruption during the 1st inning on Wednesday ... when a bat dog named Rookie stormed the field -- and it was adorable!!

The cute moment happened during the Buffalo Bisons' home game against the Lehigh Valley IronPigs at Sahlen Field ... a matchup that had Rookie filling in for bat-retrieving duties.

But, Rookie was fully prepared to go above and beyond his role to help out the Buffalo squad any way he could ... so he raced out onto the field in the middle of all the action!!

You can see the happy-go-lucky canine jumpin' with joy on the field right in front of the batter before a pitch is thrown ... and even making his way out on the pitching mound for a few seconds

Eventually, Rookie goes back to the dugout and resumes his position ... and we can't emphasize this enough, it was freakin' cute!!

BTW -- Rookie is a celeb ... he has his own Instagram page with more than 14,000 followers!!

"Tonight was a lot of fun, being with @buffalobisons," Rookie's IG page said after the game.

"I loved being able to go all over the stadium and giving out my baseball card to the fans, especially the kids."